1 2 static char help[] = "Tests not trapping an underflow\n\n"; 3 4 #include <petscsys.h> 5 #include <float.h> 6 #include <math.h> 7 8 /* From https://stackoverflow.com/questions/37193363/float-underflow-in-c-explanation */ 9 void demo(void) { 10 /* 11 FLT_MIN, FLT_MIN and the display of the floating point numbers are not portable 12 13 const char *format = "%.10e %a\n"; 14 printf(format, FLT_MIN, FLT_MIN); 15 printf(format, FLT_TRUE_MIN, FLT_TRUE_MIN); 16 */ 17 18 float f = nextafterf(1.0f, 2.0f); 19 do { 20 /* if trapping of underflow is turned on then this will generate an exception */ 21 f /= 2; 22 /* printf(format, f, f); */ 23 } while (f); 24 } 25 26 int main(int argc, char **argv) { 27 PetscFunctionBeginUser; 28 PetscCall(PetscInitialize(&argc, &argv, (char *)0, help)); 29 demo(); 30 PetscCall(PetscFinalize()); 31 return 0; 32 } 33 34 /*TEST 35 36 test: 37 TODO: Doesn't work on AArch64 targets. There's a known hardware limitation. arch-ci-linux-cmplx-single 38 args: -fp_trap 39 40 TEST*/ 41